wasm: improve clipboard fallback path

This improves handling of cut/copy/paste clipboard events,
ands allows clipboard access via the common keyboard
shortcuts.

Make the canvas be eligible for clipboard events by
setting the contenteditable attribute. Install clipboard
event handlers directly on the canvas.

Suppress Ctrl+X/C/V key event handling in the keyboard
event handler in order to make the browser generate
clipboard events. Send synthetic key events from the
clipboard event handlers to make the app copy/paste
to Qt’s clipboard at the correct time.

Access the system clipboard data using event.clipboardData.

Task-number: QTBUG-64638
Change-Id: I584b78ffa2b755b1b76e477b970255c6e5522f6a
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/plugins/platforms/wasm/qwasmeventtranslator.cpp b/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
index 3fc8f600a1..05c09ec9a0 100644
--- a/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
+++ b/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
@@ -832,6 +832,14 @@ bool QWasmEventTranslator::processKeyboard(int eventType, const EmscriptenKeyboa
         return 0;
 
     QFlags<Qt::KeyboardModifier> mods = translateKeyboardEventModifier(keyEvent);
+
+    // Clipboard fallback path: cut/copy/paste are handled by clipboard event
+    // handlers if direct clipboard access is not available.
+    if (!QWasmIntegration::get()->getWasmClipboard()->hasClipboardApi && modifiers & Qt::ControlModifier &&
+        (qtKey == Qt::Key_X || qtKey == Qt::Key_C || qtKey == Qt::Key_V)) {
+            return 0;
+    }
+
     bool accepted = false;
 
     if (keyType == QEvent::KeyPress &&